This invention relates to torque absorbers and is particularly concerned with an improved torque absorber on the discharge tubing of a submergible pump.
Submergible pumps of the centrifugal type are commonly employed to pump oil or other liquids from wells, for example, and in one type of installation the pump and its rotary motor are supported upon tubing which constitutes the discharge conduit of the pump. The reaction torque associated with the turning of the rotor of the motor and the impeller of the pump tends to cause the tubing to turn about its axis, placing stresses upon one or more threaded tubing joints close to the pump. In order to minimize such stresses and to protect the joints, and for other reasons, particularly with short discharge tubing of insufficient length to absorb the reaction torque, it has been proposed to employ a motor torque-absorber as disclosed, for example, in the copending application of Zehren, Ser. No. 175,634, filed Aug. 27, 1971. The Zehren torque absorber employs a stack of torque absorbing rings which are held between annular plates extending externally of associated tubular members capable of limited relative rotation, the plates being loosely connected by bolts which adjust the pressure on the rings. There are occasions when it is desired to provide metal-to-metal thrust bearing surfaces, which are not provided in the Zehren device, and when it is necessary to provide a torque absorber of smaller diameter than the Zehren device without restriction of the discharge flow passage. It is also desirable to minimize external protrusions, to eliminate the need for torque setting, and to reduce complexity. Although flexible couplings, torque cushioning devices and the like of various types and configurations are well known, as disclosed, for example in U.S. Pat. Nos. 919,767; 2,477,175; 2,806,365; 3,517,754; 1,552,892; 2,621,493; 2,849,871; 1,636,262; 2,703,991; 2,891,395; 1,850,210; 2,764,003; 3,183,684;
Such devices are not capable of providing the desired characteristics in a motor torque absorber for a submergible pump.